Nonspill battery vent plug

ABSTRACT

A nonspill battery vent plug is disclosed which includes a tiltable member which lifts a valve stem to close the plug whenever it is tilted. Improved means of connecting the valve stem and the weight member is provided to prevent fouling and malfunction.

United States Patent Karpal Aug. 14, 1973 [54] NONSPILL BATTERY VENTPLUG 2,981,272 4/1961 Jammal 137/43 2,717,610 9/1955 Gill 137/43 [751Invent: Km)", Cahf- 2,571,893 /1951 Kendall 136/178 [73] Assignee:Teledyne, Inc., Los Angeles, Calif.

Primary Examiner-Robert G. Nilson 22 F 1 d. l 7 I l Dec 9 1 AssistantExaminer-Edward Look [21] Appl. No.: 206,729 Attorney-Ronald W. Reaginet a1.

[52] US. Cl. 137/43, 136/178 57 ABSTRACT 51 1111. c1. 60511 16/00 [58]Field of Search 136/178; 220/44 R; A bmery Plug dlscbsed winch mcludes251/77. 137/43 38 39 a tiltable member which lifts a valve stem to closethe plug whenever it is tilted. Improved means of connect- [56] RehremesCiud ing the valve stem and the weight member is provided UNITED STATESPATENTS to prevent foulmg and malfunctwn. 2,306,974 12/1942 Oestermeyeret a1 137/43 9 Claims, 1 Drawing Figure P 30 J 32 Q 76 I it 8 52 48 46Patented Aug. 14, 1973 DAV/D L. KARPAL INVENTOR ATTORNEY NONSPILLBATTERY VENT PLUG This invention relates to nonspill battery vent plugsand more particularly to such a vent plug which is less subject tofouling during use.

Storage batteries, such as the familiar lead-acid storage battery, aresometimes used in applications in which the battery is occasionallysupported in a position other than the normal or vertical position. Forexample, when such storage batteries are used in aircraft, the batteryfrequently finds itself in a position other than absolutely vertical,and is sometimes actually upside-down when the airplane is flying in aninverted flight. It is a common practice to provide such storagebatteries with some form of nonspill vent plug so that the acid or otherelectrolyte in the battery does not leak out through the necessary ventholes when the battery is positioned in a position other than vertical.

One form of nonspill vent plug known in the art includes a housingassembly having a tubular body member which includes an inwardlyprojecting shoulder which divides the housing assembly into an upperinterior portion and a lower interior portion. The housing assembly alsoincludes upper and lower axial openings through which gas evolved in thebattery can escape when the battery is positioned vertically. A tippingweight member rests on the above mentioned shoulder and a valve stem issecured to the bottom of the weight which projects downwardly throughthe lower interior portion of the housing assembly and usually alsothrough the lower axial opening in the housing assembly. Whenever theaxis of such a plug is tilted a suitable angular distance away fromvertical, the weight member tilts relative to the housing assembly, andin so doing raises the valve stem upward relative to the housingassembly. Suitable means are provided in response to this upwardmovement of the valve stem to seal or close the opening in the bottomsurface of the housing assembly, thereby preventing electrolyte in thebattery from leaking out this hole when the battery is so tilted.

One of the problem areas encountered in the prior art with such nonspillbattery plugs has been the manner of connecting the valve stem to theweight. Obviously, the connection between the weight and the valve stemcannot be a rigid connection, since the weight is tilting laterallywhile the valve stem is moving upwardly. Thus, some form of universaljoint must be provided between these elements.

One common form of connection known in the prior art is to provide, ineffect, a ball-and-socket joint by providing a spherical orquasi-spherical cap at the top of the valve stem and providing a cavityin the bottom of the weight which has a mating spherical orquasispherical surface. This type of connection allows relative angularmovement between the axis of the weight and the valve stem while stillcausing the weight to lift the valve stem upward when the weight istilted.

However, it has been found that structures of this type have a limitedoperating lifetime. ln'operation, solid particles, such as particles oflead and lead oxide, are also carried out of the battery cell by thegases escaping through the vent plug, and over a period of time theseparticles tend to build up between the spherical surface at the top ofthe valve stem and the mating spherical surface in the weight. As thisoccurs, the valve stem is gradually held higher and higher by theweight, even when the plug is in the vertical position,

and eventually the valve becomes closed even when the plug is in avertical position. When this occurs, the evolving gas in the batterycell continues to build up until either the valve is blasted open oreven until the battery itself explodes. Obviously, this is a quiteundesirable result.

It is accordingly an object of the present invention to provide animproved nonspill battery vent plug.

It is yet another object of the present invention to provide an improvednonspill battery vent plug in which solid particles do not build upbetween the valve stem and the weight assembly.

It is yet another object of the present invention to provide an improvedjoint between the valve stem and the weight assembly in a nonspillbattery vent plug.

It is yet another object of the present invention to provide an improvednonspill battery vent plug in which, if excess pressures are built up inthe battery, the excess pressures are safely vented to the atmospherewithout destruction of either the battery or the vent plug.

Briefly stated, and in accordance with the presently preferredembodiment of this invention, a nonspill battery vent plug is providedwhich includes a housing assembly having a tubular body member includingan inwardly projecting shoulder member which defines an upper interiorportion and a lower interior portion of the housing assembly and havinga bottom surface which includes a first axial opening therein. A weightmember is provided which is positioned in the upper interior portion ofthe housing assembly and which rests freely on the shoulder member. Theweight member is adapted to tilt relative to the housing assemblywhenever the axis of the plug assembly is tilted beyond a predeterminedangle from vertical. The weight member includes a cavity in its bottomsurface and an inwardly projecting lip member separating this cavityfrom the lower interior portion of the housing assembly, the lip memberthus defining a second axial opening between the cavity and the lowerinterior portion of the housing assembly. A valve stem member isprovided which has a head portion and a stem portion. The head portionis positioned in the cavity, and has an outer diameter greater than thediameter of the second axial opening. The lower support surface of thehead portion is substantially a frusto-conical surface. The stem portionof the valve stem member extends actually through the second axialopening into the lower interior portion of the housing assembly andthrough the first axial opening in the bottom surface of the housingassembly. The stem member is lifted upward relative to the housingassembly by the weight member whenever the weight member tilts relativeto the housing assembly. Sealing means are provided responsive to upwardmovement of the valve stem member relative to the housing assembly toseal the first axial opening whenever the weight member tilts relativeto the housing assembly.

For a complete understanding of the invention, and an appreciation ofits other objects and advantages, please refer to the following detaileddescription of the attached drawing, in which the sole FIGURE shows across-sectional view of a nonspill battery vent plug assembly inaccordance with the present invention.

FIG. 1 shows a cross-sectional view of a nonspill battery vent plug 10in accordance with the present invention. The plug 10 includes a housingassembly 12 consisting of a body member 14 and a cap member 16. Bodymember 14 includes an inwardly projecting shoulder member 18 whichdivides the interior of body member 14 into an upper interior portion 20and a lower interior portion 22. Body member 14 also includes a bottomsurface 24 which has therein a first axial opening 26 extending intolower interior portion 22 of the body member 14. The function of thisfirst axial opening 26 is described below. 7

Cap member 16 is secured across the open top end of body member 14 in amanner that it may easily be snapped off, for reasons that are describedin detail below. For example, a plurality of circular holes 28 may beprovided around the top portion of body member 14. A correspondingplurality of hemispherical protuberances 30 is provided on the outersurface of a downwardly extending flange section 32 of cap member 16.When cap member 16 is positioned as shown in the FIGURE, each of thehemispherical protuberances 30 is positioned in its respective hole 28to hold cap member 16 flangibly to body member 14. Any desired number ofsuch openings and hemispherical protuberances can be used, dependingupon the degree of frangibility desired. In practice, it has been foundsatisfactory to make the plug having two such holes and hemisphericalprotuberances diametrically opposed to each other, as shown in theFIGURE.

Suitable helical threads 34 are provided around the outer surface of thelower portion of housing member 14 to enable the plug 10 to be screwedinto the usual cap openings and in a storage battery.

A tiltable weight assembly 36 is provided which normally rests uponshoulder 18 in body member 14, but which tips laterally relative to thehousing assembly 12 whenever the axis of plug 10 is tilted beyond apredetermined angle from vertical. The weight assembly 36 consists of aweight element 38 and a fulcrum element 40. Weight element 38, which ispreferably a body of revolution having a trapesoidal cross-section asshown, is formed from a dense, electrolytic resistant material, such aslead. Weight element 38 is secured to a fulcrum element 40 so thatwhenever the axis of the plug 10 is tilted to a degree that the centerof gravity of the weight assembly 36 is beyond the resulting lowestpoint of fulcrum element 40, the entire weight assembly 38 tilts aboutthis low point or fulcrum point until the sidewalls of the weightassembly 36 rest against the interior sidewalls of the upper interiorportion of body member 14.

A cavity 42, whose function is described below, is provided in thebottom surface of the weight assembly 36. Fulcrum element 40 isessentially a washer-shaped element having on its upper surface acylindrical portion 44 which projects upwardly into cavity 42 to formthe sidewalls of the cavity. The interior surface of the washer-shapedfulcrum element 40 forms an inwardly projecting lip member 46 whichseparates the cavity 42 from the lower interior portion 22 of bodymember 14, and which defines a second axial opening 48 between cavity 42and lower interior portion 22. Fulcrum element 40 further includes aplurality of radial communicating passages 50 to provide communicationbetween the lower interior portion 22 and upper interior portion 20 ofbody member 14. In the preferred embodiment, three such passages 50 areprovided which are equally angularly spaced about fulcrum element 40.

The weight element 38 may be secured to the fulcrum element 40 in anydesired manner. One preferred way is to provide a plurality ofcountersunk holes 52 extending through the bottom surface of fulcrumelement 40 and to force the lead weight element 36 downward until thelead material cold-flows into the counter-sunk hole 52 to provide thedesired fastening. In practice, it has been found satisfactory toprovide three such countersunk holes in fulcrum element 40 each of whichis positioned diametrically opposite a respective one of the passages50.

A valve stem member 54 is provided which has a head portion 56 and astem portion 58. The head portion 56 is positioned in cavity 42. As isshown in the drawing, the outer diameter of the head portion 56 isgreater than the diameter of second axial opening 48. Thus, head portion56 is retained in cavity 42.

Head portion 56 of valve stem member 54 includes a lower support surface59 which, when plug 10 is in a vertical position as shown in thedrawing, rests upon the lip member 46. In accordance with one of theprimary features of the present invention, this support surface 59 issubstantially a frusto-conical surface. In this context, the termfrusto-conical is intended to include not only a pure conical section,but also a support surface which might be, for any reason, curvedslightly upwardly or slightly downwardly. For purposes of the presentinvention, it is only necessary that the radius of curvature of the lipmember 46 at its point of contact with the support surface 59 issubstantially smaller than the radius of curvature of support surface 58at these points of contact. Thus, if the lower support surface 59 is atrue frusto-conical surface, its radius of curvature is indefinite, andthe points of contact between lower support surface 59 and lip member 48define a circle, and not a surface. As is described in more detail belowin connection with the description of the operation of plug 10, it isimportant that the contact between lower support surface 59 and lipmember 46 be as small as possible.

In accordance with another feature of the present invention, the stemportion 58 of valve stem member 54 also includes a portion 60 ofenlarged diameter which is positioned in the lower interior portion 22of housing assembly 14. Preferably, the diameter of portion 60 is thesame as that of second axial opening 48, whereby, during assembly, italso serves as a gauge to assure that the diameter of the opening 48 iscorrect and that the surface of lip member 46 is clean. An outwardlycurved deflecting surface 62 is also provided which, as is described inmore detail below, functions to prevent any solid particles which mightbe discharged by the battery from entering the cavity 42.

The structure of plug 10 is completed by a sealing washer 64 which ispositioned coaxially around the lower part of stem portion 58 of valvestem member 54. Sealing washer 64 is retained in this position by anenlarged retaining portion 66 at the bottom of valve stem member 54whose diameter is greater than the diameter of the axial opening insealing washer 64. Sealing washer 64 includes a primary sealing portion68 whose outside diameter is greater than the diameter of the firstaxial opening 26 in the bottom surface 24 of body member 14. As isdescribed in detail below, the top surface of primary sealing portion 68seals against the bottom surface 24 whenever the plug 10 is tilted.Sealing washer 64 also includes a neck portion 70 positioned as shown inthe first axial opening 26 whose outside diameter is less than thediameter of first axial opening In the preferred embodiment of theinvention, the housing assembly 12 consists of the body member 14 andthe cap member 16, the fulcrum element 40 and the valve stem member 54are all formed from the same electrolytic resistant material, such aspolypropylene. By forming all of these items from the same material, ithas been found that the likelihood of any of these surfaces freezingtogether at low temperatures is reduced. The sealing washer 64 is formedfrom a substantially softer electrolytic resistant material such asbutyl rubber. The weight member 36 is, as was noted above, formed fromlead.

When the plug is in its normal, or vertical position as shown in thedrawing, any gases evolved in the battery cell pass freely through plug10 and are vented to the atmosphere. The path of travel for such gasesis through the first axial opening 26, into the lower interior portion22 of housing assembly 14, through the passages 50 in fulcrum element 40into the upper interior portion 20 of housing assembly 12 and then outof the hole 72 in cap member 16 to the atmosphere. This path may betermed the low pressure relief path. However, if the gases evolvedinside the battery cell build up to too high a pressure, this pressureexerted on the bottom of sealing washer 64 will cause sealing washer 64to be lifted upward relative to valve stem member 54 until the primarysealing portion 68 of sealing washer 64 contacts and seals against thebottom surface 24 of body member 14. At this time, what may be termed ahigh pressure relief path still exists through plug 10 as long as plug10 is in its vertical position. This high pressure relief path is nowthrough the third axial opening 74 in sealing washer 64, into lowerinterior portion 22 of housing assembly 14, and then through passageways 50 into the upper interior portion 20 of housing assembly 12 andout the hole 72 to atmosphere. Thus, the plug 10 provides both a highpressure and low pressure relief valve function.

if the axis of plug 10 is tilted away from vertical, the weight assembly64 tilts relative to housing assembly 14, and valve stem member 54 islifted upward relative to housing assembly 14 by the force exertedthrough lip member 46 against lower sealing surface 58. When thisoccurs, the upward movement of valve stem member 54 relative to housingassembly 14 causes sealing washer 64 to be lifted until primary sealingportion 68 contacts the bottom surface 24 of body member 14, therebysealing and closing the above described low pressure relief path. At thesame time, the enlarged lower portion 66 of valve stem member 54 issealing the third axial opening 74 in sealing washer 64, thereby closingthe above described high pressure relief path. Thus, the plug 10 nowcompletely seals the battery cell in which it is employed to prevent theleakage of electrolyte out of the battery cell if the battery is held inthis tipped or inverted position.

When the battery is returned to its vertical or normal position, theweight assembly 36 tilts back relative to housing assembly 12 to theposition shown in the drawing. Valve stem member 54 is moved downward bythe combined action of gravity and by the weight assembly 36 knocking onits top surface to allow sealing washer 64 to fall to the position shownin the drawing, at which time the above described gas venting path againexists through plug 10. When this occurs and the plug 10 first opens,there is frequently an initial outrushing of evolved gas from thebattery cell which can carry solid particle matters, such as smallparticles of lead, out through the above described low-pressure ventingpath. Such a flow of gases, and also any solid particles carried by thegases, is deflected outwardly by the deflecting surface 62 to keep thesesolid particles from getting into cavity 42 or between the lip member 46and lower sealing surface 59 of valve stem member 54. Thus, the abovedescribed undesirable build-up of such materials, which might lead toundesired lifting of valve stem member 54 is prevented. However, inaccordance with another feature of the present invention, even if anysuch particles do manage to pass through the second axial opening 48into cavity 42, they tend to eventually settle on the horizontal surface76, which thus forms a reservoir for such particles, rather than foulingthe actual contact point between lip member 46 and lower support surface59.

Finally, it is noted that if the plug 10 is sealing for any reason, andif the pressure of gases within the cell becomes too high, thesepressures will cause force on the bottom of the lower enlarged portion66 of valve stem member 54 to drive this member upwardly completelythrough the third axial opening 74 in sealing washer 64. When thisoccurs, this excess pressure will effectively blast the weight assembly36 out against cap member 16 of housing assembly 12. As was describedabove, cap member 16 is secured to the body member 14 in a frangiblemanner, and when this occurs, cap member 16 is forced off and the plug10 is effectively popped open to provide the necessary venting functionto keep the battery cell from exploding.

The pressure at which the plug 10 so pops open is a function of thesoftness or pliability of the material from which sealing washer 64 isformed and of the difference between the inside diameter of third axialopening 74 and the outside diameter of enlarged end portion 66 of valvestem member 54. These parameters can easily be determined empirically bythose skilled in the art to provide the pop-open function at any desiredpressure. For lower pressure, the material from which sealing washer 64is formed should be softer or more pliable and the diameter of the axialopening 74 should be larger relative to the diameter of lower endportion 66. Conversely, for a higher pop-open" pressure, the materialshould be harder and the diameter of lower end portion 66 should begreater.

While the invention is thus disclosed and the pres ently preferredembodiment described in detail, it is not intended that the invention belimited to this shown embodiment. Instead, many modifications will occurto those skilled in the art which lie within the spirit and scope of theinvention. It is accordingly intended that the invention be limited inscope only by the appended claims.

What is claimed is:

l. A nonspill battery vent plug, comprising, in combination:

a housing assembly including a body member in which said body membercomprises a tubular side wall having an inwardly projecting shouldermember defining an upper interior portion and a lower interior portionand a bottom surface having a first axial opening therein;

a weight member positioned in said upper interior portion of saidhousing assembly and resting freely on said shoulder member, said weightmember being adapted to tilt relative to said housing assembly wheneverthe axis of the plug is tilted beyond a predetermined angle fromvertical, said weight member including a cavity in its bottom surfaceand an inwardly projecting lip member separating said cavity from saidlower interior portion of said housing assembly and defining a secondaxial opening between said cavity and said lower interior portion ofsaid housing assembly;

a valve stem member having a head portion and a stem portion, said headportion being positioned in said cavity, having an outer diametergreater than the diameter of said second axial opening and having alower support surface which rests on said lip member, said lower supportsurface being substantially a frusto-conical surface having a radius ofcurvature at its points of contact with said lip member which issubstantially greater than the radius of curvature of said lip member,said stem portion extending axially through said second axial openinginto said lower interior portion of said housing assembly and throughsaid axial opening, whereby said valve stem member is lifted upwardrelative to said housing assembly by said weight member whenever saidweight member tilts relative to said housing assembly; and

sealing means responsive to upward movement of said valve stem memberrelative to said housing assembly to close said first axial openingwhenever said weight member tilts relative to said housing assembly.

2. The invention of claim 1 which further comprises deflection means fordeflecting away from said second axial opening any stream of gases andsolid particles carried by such gases which enter said first axialopenmg.

3. The invention of claim 2 in which said deflection means comprises anenlarged diameter portion of said valve stem member which includes anoutwardly curved deflecting surface.

4. The invention of claim 3 in which said sealing means comprises asealing washer including a primary sealing portion having an outsidediameter greater than the diameter of said first axial opening, a neckportion having a diameter smaller than the diameter of said first axialopening and a .third axial opening whose diameter is greater than thediameter of said stern portion of said valve stem member, with saidsealing washer being positioned co-axially with said stem portion ofsaid valve core member with said neck portion positioned in said firstaxial opening, said primary sealing portion positioned beneath thebottom surface of said housing assembly and said valve stem memberincluding a retaining portion at its bottom end whose diameter isgreater than the diameter of said third axial opening to retain saidsealing washer in said co-axial position.

5. The invention of claim 4 in which said weight member comprises anassembly of a weight element and a fulcrum element secured to the bottomof said weight element, said fulcrum element including a washer-shapedportion whose inner surface is said lip member and whose central openingis said second axial opening, said fulcrum having a plurality ofchannels therein to provide communicating passages between the lowerinterior portion and the upper interior portion of said housingassembly.

6. The invention of claim 5 in which said fulcrum element furtherincludes a cylindrical portion which forms the side walls of said cavityand in which said housing assembly and said fulcrum element are formedfrom the same electrolytic material.

7. The invention of claim 4 in which said housing assembly furthercomprises a cap member which is frangibly secured across the top end ofsaid body member.

8. The invention of claim 7 which further comprises means responsive topressure in excess of a predetermined maximum pressure to force saidretaining portion of said valve stem member through said third axialopening to allow said weight member to rise in response to excesspressure to force said cap member from the top end of said body member,thereby venting any excess pressure to the atmosphere.

9. The invention of claim 8 in which said weight member comprises anassembly of a weight element and a fulcrum element secured to the bottomof said weight element, said fulcrum element including a washer-shapedportion whose inner surface is said lip member and whose central openingis said second axial opening, said fulcrum having a plurality ofchannels therein to provide communicating passages between electrolyticresistant material.

1. A nonspill battery vent plug, comprising, in combination: a housingassembly including a body member in which said body member comprises atubular side wall having an inwardly projecting shoulder member definingan upper interior portion and a lower interior portion and a bottomsurface having a first axial opening therein; a weight member positionedin said upper interior portion of said housing assembly and restingfreely on said shoulder member, said weight member being adapted to tiltrelative to said housing assembly whenever the axis of the plug istilted beyond a predetermined angle from vertical, said weight memberincluding a cavity in its bottom surface and an inwardly projecting lipmember separating said cavity from said lower interior portion of saidhousing assembly and defining a second axial opening between said cavityand said lower interior portion of said housing assembly; a valve stemmember having a head portion and a stem portion, said head portion beingpositioned in said cavity, having an outer diameter greater than thediameter of said second axial opening and having a lower support surfacewhich rests on said lip member, said lower support surface beingsubstantially a frusto-conical surface having a radius of curvature atits points of contact with said lip member which is substantiallygreater than the radius of curvature of said lip member, said stemportion extending axially through said second axial opening into saidlower interior portion of said housing assembly and through said axialopening, whereby said valve stem member is lifted upward relative tosaid housing assembly by said weight member whenever said weight membertilts relative to said housing assembly; and sealing means responsive toupward movement of said valve stem member relative to said housingassembly to close said first axial opening whenever said weight membertilts relative to said housing assembly.
 2. The invention of claim 1which further comprises deflection means for deflecting away from saidsecond axial opening any stream of gases and solid particles carried bysuch gases which enter said first axial opening.
 3. The invention ofclaim 2 in which said deflection means comprises an enlarged diameterportion of said valve stem member which includes an outwardly curveddeflecting surface.
 4. The invention of claim 3 in which said sealingmeans comprises a sealing washer including a primary sealing portionhaving an outside diameter greater than the diameter of said first axialopening, a neck portion having a diameter smaller than the diameter ofsaid first axial opening and a third axial opening whose diameter isgreater than the diameter of said stem portion of said valve stemmember, with said sealing washer being positioned co-axially with saidstEm portion of said valve core member with said neck portion positionedin said first axial opening, said primary sealing portion positionedbeneath the bottom surface of said housing assembly and said valve stemmember including a retaining portion at its bottom end whose diameter isgreater than the diameter of said third axial opening to retain saidsealing washer in said co-axial position.
 5. The invention of claim 4 inwhich said weight member comprises an assembly of a weight element and afulcrum element secured to the bottom of said weight element, saidfulcrum element including a washer-shaped portion whose inner surface issaid lip member and whose central opening is said second axial opening,said fulcrum having a plurality of channels therein to providecommunicating passages between the lower interior portion and the upperinterior portion of said housing assembly.
 6. The invention of claim 5in which said fulcrum element further includes a cylindrical portionwhich forms the side walls of said cavity and in which said housingassembly and said fulcrum element are formed from the same electrolyticmaterial.
 7. The invention of claim 4 in which said housing assemblyfurther comprises a cap member which is frangibly secured across the topend of said body member.
 8. The invention of claim 7 which furthercomprises means responsive to pressure in excess of a predeterminedmaximum pressure to force said retaining portion of said valve stemmember through said third axial opening to allow said weight member torise in response to excess pressure to force said cap member from thetop end of said body member, thereby venting any excess pressure to theatmosphere.
 9. The invention of claim 8 in which said weight membercomprises an assembly of a weight element and a fulcrum element securedto the bottom of said weight element, said fulcrum element including awasher-shaped portion whose inner surface is said lip member and whosecentral opening is said second axial opening, said fulcrum having aplurality of channels therein to provide communicating passages betweenthe lower interior portion and the upper interior portion of saidhousing assembly, said fulcrum element further including a cylindricalportion which forms the side walls of said cavity, said fulcrum elementand said housing assembly both being formed from the same electrolyticresistant material.